That work well during long time, it's reliable and and connect quickly to the RPi3 when the RPi3 is running normally.

BUT if after a power outage for the whole house, the RPi3 reboots and at the same time the NodeMCU also, then WiFi communication is not done. I have to restart the NodeMCU separately when RPi3 is in normal operation again.
It's necessary to change setup in my sketch but where ...?

@marsault6 I prepared a pr, referenced from the issue, that fixes the crash at my setup. It's not the optimal solution, but seems to do the trick.
If you're handy with installing your own libraries you could give that a try.